From December to March, run-off from seven rivers transforms this 210,000 sq km area into an immensely productive wetland half the size of France. Then, starting in June, the tide literally turns as the waters begin to recede, trapping many of the region's 600 fish species in increasingly smaller ponds, lakes and channels. From July to December, the wildlife viewing is extraordinary as ever-growing numbers of animals gather around shrinking bodies of water to drink and feed on the huge quantities of trapped fish, producing a concentration of fauna not often witnessed in the New World.

This is when wading birds - ten species of heron and egret, three species of stork, and six species of ibis and spoonbill - begin nesting in gigantic, noisy colonies that can cover square kilometres. And almost more impressive is the sight of the region's 20 million black caimans amassing around every water hole, reaching densities of 150 caimans per sq km (the highest levels in the world).

Equally drawn to water holes are capybaras, anacondas (reaching up to 7m in length), marsh deer and jaguars; but do not overlook the fact that this entire unique region is fabulously rich in wildlife. What distinguishes the Pantanal ecologically is that it combines elements of central Brazil's cerrado savannahs and Paraguay's chaco scrublands - along with an endless maze of ponds, lakes, rivers, forests and islands - to create a habitat for 200 species of mammal and 650 species of bird.

Annual flooding mostly saves this area from development and disturbance, and even to this day it remains sparsely populated by very large scattered ranches, fazendas, that have grazed cattle here during the dry season for more that 200 years. This area is called "South America's Wild West" and it is still a wild place where pumas, ocelots, maned wolves, giant anteaters and crowned eagles coexist peacefully with light human use.

The Amazon may attract more fame and glory, but the Pantanal is a better place to see wildlife. In the Amazon, the animals hide in the dense foliage, but in the open spaces of the Pantanal, wildlife is visible to the most casual observer.

The Pantanal has few people and no towns. Distances are so great and ground transport so poor that people get around in small airplanes and motorboats; 4x4 travel is restricted by the seasons. The seasonal flooding has also made systematic farming impossible and has severely limited human incursions into the area. Instead, it provides an enormously rich feeding ground for wildlife.

The best way to approach the Pantanal is along the Transpantaneira Road, which dries out in July long enough that you can drive (or cycle) the 150km from Poconé near Cuiabá, south to Porto Jofre on the Rio Cuiabá.